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T. Colin Campbell Center for Nutrition Studies
Tamoxifen’s Untold Story

I receive many newspaper clippings on nutrition, sent by friends and colleagues, and coming from many parts of the world. As a scientist, however, I must say I’m often dismayed by the degree of misinformation I find in these reports. While many in my profession would like to think that this is a “media problem,” I have to admit that it is also a “science problem.”

Among the articles on my desk, those that talk about the promise of the new drug tamoxifen perhaps best illustrate my point. Tamoxifen is a matter of growing interest for the American public and the scientific community. The National Cancer Institute (NCI) of NIH recently invested about $68 million to test the ability of this new drug to prevent breast cancer. About 16,000 women, thought to be at higher than average risk for breast cancer, are being recruited to take a couple of tamoxifen pills daily for five years. Already, more than 11,000 have signed up despite serious indications that risks may easily outweigh benefits.

It now turns out, for example, that among tamoxifen users there is a three to fourfold greater risk of uterine cancer, among other possible health hazards. In a recent report on cancer risk among tamoxifen users, NCI, which provides the funds for this new tamoxifen study, has estimated that although 132 cases of breast cancer might be prevented or delayed, there will be 83 cases of uterine cancer. Other hazards have not yet been factored into this equation, thus leaving speculation that there may be more harm than good coming from this trial.

The Story Behind the News

This is a story not only about drugs designed to prevent or cure diseases. It is also about the institution of science ignoring the possibilities and promises of nutrition to prevent, perhaps even to reverse, disease. It is about the discovery of drugs or procedures having commercial value. It is about scientists not choosing to investigate their own faulty eating habits.
Science is ignoring the possibilities and promises of nutrition

It is about failing to let you, the consumer, know what you can do to improve your own health with much less cost. It is also about most of us not being willing to entertain new ideas, especially those that challenge our favorite ways of thinking and doing. All of this creates confusion and deters real progress.

Because this is largely a science problem, let’s take a look at the scientific crux of the issue”experimental control.” No principle of science is more revered than how we “control” our studies. Control means designing our experiments or analyzing our data so that all factors not under study and possibly affecting our results are under “control.” In effect, they are evened out over the whole experiment.

Randomizing Our Ignorance

In very simple experiments (usually called “randomized clinical trials”) we have a treatment group and a control group. The treatment group receives the test chemical or procedure, while the control group receives a placebo that essentially has no effect. In a more complicated study, we may search for possible causes of disease among free living human populations. Here, scientists usually begin their studies with some preconceived ideas about which causes to look for (among countless possibilities) so they can know which kinds of measurements to make. Then, whenever possible, during the final analysis of their data, they “control” or balance out, by statistical means, everything except their preconceived factor of interest.

In both kinds of studies, the idea of “control” is essentially the same. That is, scientists investigate single causes of disease instead of combinations obviously involved. Each scientist chooses which factor or small number of factors to investigate depending on all sorts of reasons, many of which are relatively unscientific. They then design studies and analyze results to balance out, or control, everything else. The balanced-out factors remain hidden from analysis. Unfortunately, it is often these hidden factors or enormous combinations of these factors that matter most in causing disease in the first place.

We scientists often ignore things we know nothing about as well as things we are prejudiced against.

Our choice of which factors to study or test is never random, even though much else in the experiment is. We often make our choices on the basis of available funds, personal preferences, and/or convenient opportunities. We scientists often ignore things we know nothing about as well as things we are prejudiced against. These ignored things are “controlled” out of the experiment by randomly and evenly distributing them across all groups. I call it randomizing our ignorance.

What I am getting at here is that our research most of the time is too “reductionist,” too narrowly focused, too opportunistic. We “reduce” our forest into tiny bits, maybe the sub-cellular particles of a certain cell, of a certain part of a tree, of a certain species of tree, of a certain geoclimatic area, and then speculate on forests in general.

Tamoxifen, a Case Study

Now, let’s return to our story on tamoxifen, which illustrates this central problem of science. While much evidence shows that breast cancer is almost certainly caused by a huge number and variety of dietary and lifestyle factors, science instead focuses on very simple but very expensive ideas, like tamoxifen.

Original interest in this drug arose when it was shown to slightly delay the recurrence of breast cancer among women already treated for a first cancer (some investigators like to call this delay a “cure” for breast cancer!). These early findings were enthusiastically welcomed because the side-effects appeared to be much less than the side-effects often observed for the very troublesome cytotoxic cancer drugs usually used. However, this enthusiasm now has been extended to the use of tamoxifen for healthy women whose only “problem” is that they are supposedly at higher risk of breast cancer than the general population.

Most news accounts of tamoxifen that I have read omit one very important and well-known observation. Namely, tamoxifen is thought to act on breast cancer by interfering with the ability of estrogen, mostly a female hormone, to stimulate breast cancer growth. But low-fat diets, like those provided by plant-based foods, also can do much the same thing. It appears they influence these same estrogen effects on breast cancer, but do so much more safely and comprehensively, that is naturally, than does tamoxifen. In so doing, the dietary approach should cast a much wider net of beneficial effects, while simultaneously minimizing unwanted side effects.

Why We Go for Gimmicks

Why do we go for gimmicks rather than adopt a healthy dietary strategy, especially with a disease that is so emotionally and economically devastating? We must first find better ways to understand the big picture if ever we are to reduce public confusion. We must clear from our vision the personal, political, and overly zealous economic motivations. Then, and only then, can we afford to undertake research on some of the details to see how it all fits together. I believe that much of the public confusion on health issues is due to serious structural faults in our system of scientific investigation. Here is where the problem begins and where many of the solutions can be found. Only then will we also find a solution for our “media problems.”


  • Raloff, J., “Tamoxifen Turmoil. New Issues Emerge as Health Women Volunteer to Take a Potent Drug.” Science News 146:268-269.
  • Smigel, K., Ulbrich, S. 1994. “News: Breast Cancer Prevention Trial Will Resume.” J. National Cancer Institute 86:961-963.
  • Touchette, N. 1992. “Tamoxifen Resistance in Breast Cancer.” J. NIH Research 4:67-72.

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